The invention concerns a fuel filter insert with a prefilter element and a main filter element as well as a fuel filter with such a fuel filter insert.
DE 10 2008 048 228 A9 discloses a fuel filter with a fuel filter insert comprising a prefilter element and a main filter element that can be arranged concentrically to the longitudinal axis of the fuel filter or positioned one behind the other in axial direction. The fuel prefiltered by the prefilter element is supplied pressure-loaded to the main filter element by means of a fuel pump arranged outside of the filter housing. A pressure region comprising the prefilter element and a pressure region comprising the main filter element of the fuel filter insert are separated from each other by a filter housing of a complex construction.
U.S. Pat. No. 3,900,400 B discloses a fluid filter with two filter elements that are arranged in the filter housing one atop the other in the direction of the longitudinal axis of the fluid filter and that can be exchanged independent of each other. The interior of the filter housing is separated by an end disc of a lower filter element and by a housing clamping plate, supported on the end disc resiliently by a spring, into two high-pressure regions in which one of the filter elements is arranged, respectively.
EP 0 852 158 A1 discloses a fuel filter with a fuel filter insert with two filter elements that are arranged fluidically connected one behind the other and arranged one atop the other in the direction of the longitudinal axis of the fuel filter insert.
WO 2006/070221 A1 discloses a further fuel filter with a prefilter element and a main filter element which are arranged concentric relative to the longitudinal axis of the fuel filter.
Similar fuel filters are disclosed in DE 20 2006 004 527 U1 and EP 1 485 605 B1.
The known fuel filter inserts are not very compact and can be handled only with difficulty. Moreover, for accommodating them, a filter housing with a complex and therefore expensive constructive configuration is required.